why would it be guitar center? I don't see anything that would give them a competitive advantage. I only ever go there to try guitars. if I really like one, I'm probably just going to go home and order a pristine example online. there's no way I'm gonna drop $800+ on a guitar that's been sitting in the open air and manhandled by customers for an unknown length of time. it's not a local business, so I don't even feel bad about it.
as I see it, a brick-and-mortar retailer has three possible functions: an inventory, a showroom, and a service center. it's hard even for a large physical store to beat an online retailer on inventory. guitar center in particular does not seem to be trusted as a service center. musicians I know would only take their guitars there for repairs/setups if there was literally no other option. this basically makes it just a showroom. it's hard to make money showing other people's products that can be bought cheaper elsewhere.
it seems to me that the only way forward for third party brick-and-mortars is to somehow monetize the showroom role. maybe they could get paid directly by the manufacturer to show their products or have some sort of referral system. integrate it with a service center and let the customers play with the display guitars while you fix theirs.